The Bolt Circle Diameter (BCD) is the diameter of the circle that passes through the centre of the bolts on your chainring. You may need to know the BCD in order to obtain a new chainring. Many chainrings have the BCD shown on them but if it isn't, you'll need to calculate it.

Cleaning your ChainKeeping your chain clean will make it last longer and give a smoother gear change. The chain can be cleaned on or off the bike and is down to personal choice.On the bikeThis method uses a device that is placed on the chain whilst on the bike. It contains brushes and rollers that flex the chain and run it through a reservoir of solvent.Off the bikeIf you are...

Chains wear - fact! The rate of wear (or more specifically 'stretch') depends on how clean you keep your chain and drive-train together with the type of riding you do.
From experience I can say that most people think their chain is ok and isn't unduly worn but the reality is somewhat different. I've lost count of the number of times I've had to replace chain rings and cassettes due...

Derailleur Gears may look to be complicated devices but are actually quite simple in practice. The chain is pushed sideways onto the selected sprocket or chainring by using a friction or indexed lever. Modern bikes use an indexed system where a click on the shifter selects the desired sprocket. The gear shifter may be integrated into the brake levers.
If your gear indexing has suddenly started misbehaving, firstly check that...